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                        <h1 id="">内存管理原则</h1>
<h2 id="">本小节知识点:</h2>
<ol>
<li>【掌握】内存管理原则</li>
<li>【掌握】多对象内存管理</li>
<li>【掌握】set方法内存管理</li>
<li>【掌握】dealloc方法的内存管理</li>
</ol>
<h2 id="1">1.内存管理原则</h2>
<ul>
<li><p>苹果官方规定的内存管理原则</p>
<ul>
<li><p>谁创建谁release :</p>
<ul>
<li>如果你通过alloc、new、copy或mutableCopy来创建一个对象，那么你必须调用release或autorelease</li>
</ul>
</li>
<li><p>谁retain谁release:</p>
<ul>
<li>只要你调用了retain，就必须调用一次release</li>
</ul>
</li>
</ul>
</li>
<li><p>总结一下就是</p>
<ul>
<li>有加就有减</li>
<li>曾经让对象的计数器+1，就必须在最后让对象计数器-1</li>
</ul>
</li>
</ul>
<hr>
<h2 id="2">2.多对象内存管理</h2>
<ul>
<li><p>单个对象的内存管理, 看起来非常简单</p>
</li>
<li><p>如果对多个对象进行内存管理, 并且对象之间是有联系的, 那么管理就会变得比较复杂</p>
</li>
<li><p>其实, 多个对象的管理思路 跟很多游戏的房间管理差不多</p>
<ul>
<li>比如斗地主 \ 劲舞团 \ QQ音速
<img src="images/a5/534347_001415_6_lit.jpg" alt=""></li>
</ul>
</li>
<li><p>总的来说, 有这么几点管理规律</p>
<ul>
<li>只要还有人在用某个对象，那么这个对象就不会被回收</li>
<li>只要你想用这个对象，就让对象的计数器+1</li>
<li>当你不再使用这个对象时，就让对象的计数器-1</li>
</ul>
</li>
</ul>
<hr>
<h2 id="3set">3.set方法内存管理</h2>
<ul>
<li>(1)retain需要使用的对象</li>
<li>(2)release之前的对象</li>
<li>(3)只有传入的对象和之前的不同才需要release和retain</li>
</ul>
<pre><code class="lang-objc">- (<span class="hljs-keyword">void</span>)setRoom:(Room *)room
{
    <span class="hljs-comment">// 避免过度释放</span>
    <span class="hljs-keyword">if</span> (room != _room)
    {
        <span class="hljs-comment">// 对当前正在使用的房间（旧房间）做一次release</span>
        [_room release];

        <span class="hljs-comment">// 对新房间做一次retain操作</span>
         _room = [room retain];
    }
}
</code></pre>
<h2 id="4dealloc">4.dealloc方法的内存管理</h2>
<pre><code class="lang-objc">- (<span class="hljs-keyword">void</span>)dealloc
{
    <span class="hljs-comment">// 当人不在了，代表不用房间了</span>
    <span class="hljs-comment">// 对房间做一次release操作</span>
    [_room release];
    [<span class="hljs-keyword">super</span> dealloc];
}
</code></pre>

                    
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